The present invention pertains to the manufacture of the components for a vehicle frame assembly and, more particularly, to the continuous roll forming of frame sidebars, crossbar members, and bracket members, all comprising channel sections.
The present invention relates to use of a computer controlled roll former and an associated computer controlled hole punching apparatus to form the sidebar components, ganged bracket members, and ganged crossbar members, with the ganged members cut to form individual brackets and crossbars after all the preliminary forming is completed.
A typical frame member for a vehicle chassis includes a pair of parallel sidebars or side rails connected by transverse crossbars with the connections effected by brackets if the connections are made by bolting or riveting. Welded frames may not require connecting brackets. However, in the truck industry, bolted connections are preferred and predominate.
For many years, truck fame components were formed primarily by stamping individual pieces utilizing hard tooling designed to form sequentially identical component parts. Truck frame components are typically made of channel members, but within a particular frame assembly, both the size and the gauge of the channels for the respective sidebars, crossbars and brackets may vary. Thus, three or more sets of hard tooling may be required for stamping the components of a typical frame assembly. For a bolted (or riveted) frame assembly, the bolt holes are punched in the individual components after the components are stamped and often prior to final heat treating. Because the bolt holes may be punched with different punching apparatus, there is often a problem of bolt hole match-up at assembly. In addition, heat treating the components after the holes have been punched may result in further changes in bolt hole position and/or size.
All of the foregoing problems may be compounded where the components are supplied by more than one manufacturer or are made at different locations. In addition, truck manufacturers often desire essentially identical frame members in an order to be provided with varying bolt hole patterns depending on the engine, truck body and other intended uses for a particular frame. This also propounds the problems of bolt hole position and match-up.
In accordance with the present invention, a vehicle frame assembly, comprising sidebars, crossbars and connecting brackets, is manufactured using a computer controlled flexible roll former that eliminates the need for hard tooling. The shorter frame assembly components, namely the crossbars and the brackets, are formed as multi-piece gang members that are hole-punched and, if necessary, offset-formed before being cut into respective individual crossbars and brackets.
In one embodiment of the method of the present invention, the method comprises the steps of (1) forming a steel strip in the roll former to a first channel shape, (2) cutting the first channel shape to provide a sidebar, (3) adjusting the roll former and forming a steel strip to a second channel shape, (4) cutting the second channel shape to provide a multi-bracket gang member, (5) adjusting the roll former and forming a steel strip to a third channel shape, (6) cutting the third channel shape to provide a multi-crossbar gang member, (7) punching a plurality of attachment holes in the sidebars, in the bracket gang member, and in the crossbar gang member, and (8) cutting the bracket gang member and the crossbar gang member to provide respective individual brackets and crossbars.
In one variation of the foregoing method, each of the forming steps is performed on the same strip. The method may also include the step of heat treating the sidebars, the bracket gang member, and the crossbar gang member before punching. Preferably, the method comprises cutting the first channel shape to provide a plurality of pairs of sidebars, cutting the second channel shape to provide a plurality of bracket gang members, and cutting the third channel shape to provide a plurality of crossbar gang members.
In a variant method of the present invention, vehicle frame assemblies each including a pair of sidebars, a plurality of crossbars for interconnecting the sidebar pair, and a plurality of connection brackets, all formed of channel sections, are manufactured by a method comprising the steps of (1) forming sidebars, ganged bracket members, and ganged crossbar members utilizing an adjustable computer controlled roll former, (2) heat treating, if necessary, the sidebars, bracket members and crossbar members, (3) punching connection holes in the sidebars, bracket members and crossbar members utilizing a computer controlled punch, and (4) cutting the bracket members and crossbar members to form individual brackets and crossbars.
This variant method may also include the step of, prior to cutting the crossbar members, forming offset portions at selected positions of the crossbar members. The offset portions are preferably formed at crossbar end positions defined by the subsequent cutting step. The offset forming step may comprise vertical offsetting or horizontal offsetting.
A further embodiment of the method of the present invention comprises manufacturing a plurality of vehicle frame assemblies, each including a pair of sidebars, a plurality of crossbars and a plurality of brackets, including the steps of (1) forming the sidebars to individual cut lengths, (2) forming the crossbars and the brackets, respectively, in initial ganged crossbar members and ganged bracket members, (3) punching the side bars, crossbar members, and bracket members in a computer controlled punch device to form connection holes, and (4) cutting the crossbar members and the bracket members to form individual crossbars and brackets.
Preferably, the forming step of the foregoing method comprises roll forming. The roll forming step preferably utilizes a computer-controlled adjustable roll former. The method may also include the step of heat treating the sidebars, crossbar members and bracket members prior to punching. The heat treating step is preferably performed after the roll forming step.